Before you can make a record, you'll first need to enable tracking for sun cream in the room settings. To do this head in to Setup -> Rooms -> Room Settings. Here you can enable sun cream tracking by checking the box.
Once you've enabled tracking you can then record sun cream application for a child. To do this head to your nursery overview, click in the room the child is in and click on their photo. This will bring up a side bar on the right where you can click status and then apply cream.
Once you've clicked this, you can chose the SPF, which will then finish the record and appear on the child's activity tab.